ftp포트만 열려있는데 다른 서버에서

<?php// define some variables$local_file = 'local.zip';$server_file = 'server.zip';// set up basic connection$conn_id = ftp_connect($ftp_server);// login with username and password$login_result = ftp_login($conn_id, $ftp_user_name, $ftp_user_pass);// try to download $server_file and save to $local_fileif (ftp_get($conn_id, $local_file, $server_file, FTP_BINARY)) {    echo "Successfully written to $local_file\n";} else {    echo "There was a problem\n";}// close the connectionftp_close($conn_id);?>